libANGLE: Add a unique ID to the Surface This is needed when capturing Pbuffer calls. Bug: angleproject:4964 Change-Id: Id9f35683bf887f08f916de69bbab8c414e5e8872 Reviewed-on: https://chromium-review.googlesource.com/c/angle/angle/+/3711740 Reviewed-by: Cody Northrop <cnorthrop@google.com> Commit-Queue: Gert Wollny <gert.wollny@collabora.com> Reviewed-by: Shahbaz Youssefi <syoussefi@chromium.org>